best carb for 1098..

[Boris64]

Bmc,

Thanks for the message.

The carb and manifold are as the earlier photos.

I'm planning on fitting a Hif 38 carb with alloy manifold to the existing 1098 head having cut the inlet off a standard combined manifold.

Opening up the throat is a perhaps rather extreme description of what you suggested earlier ie radius the inlet.

Have I misunderstood something?

Thanks.

Pete

[Boris64]

Sorry, this is the much more useful photo of the inlet manifold.

Will this fit the 1098 head or do I need to go shopping again?

Thanks

Pete[frame][/frame]

[bmcecosse]

Yes it will fit - either machine for the rings - or discard them. The inlet to the carb should be gently radiused - I use a half-round file followed by wet/dry etc , no machinery!

[Boris64]

Bmc,

Thanks for confirmation.

Are the inlet ports in the 1098 head the same size as those in the alloy manifold (1.25" from photo) and it's just minor machining to accommodate the rings?

If so can I discard the rings?

Thanks

Pete

[bmcecosse]

Just discard the rings - some locate the manifold with small dowel pins - but usually the studs locate it well enough. By all means open up the head ports slightly to match the manifold. Again - mounted points and electric drill......

[Boris64]

Bmc,

Thanks, next stop is to take the existing carb and manifold off and see what I need to deal with.

I believe I have everything now so fingers crossed.

Pete

[Boris64]

A quick note to complete this thread and to thank all for their advice.

The full story and photos are in Boris 64 resto thread.

In short

1. Took advice
2. Bought the bits on ebay
3. Cut the inlet from a combined manifold
4. Removed 1.25" SU and combined manifold in 1 piece
5. Fitted exhaust only manifold
6. Fitted Hif38 carb on inlet manifold
7. Connected hoses and cables
8. Started engine
9. Tuned as advice on this forum


The result-

Very easy to do, noticeably faster acceleration, noticeably more noise.

Replaced 1.25" SU

All good fun

Pete[frame][/frame]

[bmcecosse]

Well done - check that plastic pipe on the vacuum connection doesn't just 'suck flat' when you rev up and then close the throttle.....

[Boris64]

Bmc,

Thanks for the positive reply and earlier advice.

My final line although rather unclear was the sad confession however.

I refitted the 1.25" SU as the noise was too much for the junior mechanic as she uses the car every day

Pete

[bmcecosse]

Just look for a quieter air filter - ex marina/Maestro/Princess -something like that. I have the same filter - can't say I notice the noise - mainly because of the straight through big bore exhaust........

[MikeNash]

Boris,
As I've got all the bits you've fitted except the big bore carb, can you tell us how it all goes with the standard 1.25 inch SU. Any improvements remaining?
Regards, MikeN.

[bmcecosse]

The performance will be limited by the airflow through the carb/airfilter combo - so top end will be no better than before, but there should be more urge at lower revs - until that airflow limit is reached. I'm Interested to hear how that works out in practice too!

[Boris64]

Bmc, Mike,

It didn't occur to me to retain the improved separate manifold and just refit the 1.25" carb how easy would that have been!!!

I just put all the original kit back on in one piece as it came off.

I can't comment on the hybrid which I think you're describing Mike.

Pete

[bmcecosse]

You will need an adapter plate for carb to manifold - but easy enough to make up.

[Boris64]

Bmc,

Thanks, I noticed that my carb to combined manifold studs are north and south, whereas those on the separate inlet manifold are at 2.00 and 8.00, if you'll permit the mixed metaphor.

Pete

[bmcecosse]

Hence the need for an adapter plate...